1. Field of the Invention
The invention relates to a sensor module, which has a sensor with a sensor output for outputting a measurement signal for a physical quantity, whereby the sensor output is connected to an output terminal directly or via at least one signal processing stage provided for processing the measurement signal. In addition, the invention relates to a method for monitoring the function of a sensor module, which has a sensor by means of which a measurement signal for a physical quantity to be determined is generated and applied to an output terminal in an unchanged form or in processed form—after at least one linear signal processing step and/or at least one nonlinear signal processing step are performed.
2. Description of the Background Art
A sensor module is disclosed in European Pat. No. EP 0 962 748 B1, which corresponds to U.S. Pat. No. 6,424,143, and which is incorporated herein by reference. The sensor module is formed as a monolithic integrated circuit, which has a magnetic field sensor for detecting a magnetic field generated by an external transducer, a measuring amplifier, and an evaluation circuit, which is connected to internal measurement points of the integrated circuit. The evaluation circuit has a modulator for modulating the output measurement signal. In order to output the information available in the internal evaluation circuit, the internally determined measurement values are passed as modulation signals to the modulator, which superimposes these on the digital output measurement signal. With the aid of information passed on to the outside in this manner, it is possible to reach conclusions on the instantaneous operating point of the circuit and to detect changes that move in the direction of the operating limits of the sensor module, in a timely fashion before complete failure of the sensor occurs. Although the sensor module has proven its value in practice, it nevertheless has disadvantages. Thus, the information passed to the outside enable only a limited check of sensor module functionality.